The present invention relates to a semiconductor device and a manufacturing technology thereof. More particularly, it relates to a semiconductor device having a field effect transistor formed in an active region surrounded by a trench type element isolation part formed in a main surface of a semiconductor substrate, and a technology effectively applicable to manufacturing thereof.
With miniaturization of semiconductor elements for use in LSI (Large Scale Integration), miniaturization of an element isolation part for electrically isolating respective semiconductor elements also proceeds. In recent years, there has been widely used for LSI, the trench isolation method which can be expected to achieve higher integration and to have a more improved isolation capability as compared with the LOCOS (Local Oxidation of Silicon) method.
For example, US Patent Application No. 2007/0111470 (Patent Document 1) discloses the following method: at the inner wall of a trench, a silicon nitride film (liner layer) is formed; then, only at the bottom of the trench, an oxide film (oxide layer) is formed; subsequently, the inside of the trench is filled with a silicon oxide film (silicon oxide layer), thereby to form a trench type element isolation part.
Further U.S. Pat. No. 7,645,679 (Patent Document 2) discloses the following method: at the inner wall of a trench, a thermal oxidation film (thermal oxidation layer) is formed; further, thereover, a silicon-rich oxide film (silicon rich oxide) is formed; then, the inside of the trench is filled with an oxide film (oxidation isolation layer), thereby to form a trench type element isolation part.
Still further, U.S. Pat. No. 6,331,472 (Patent Document 3) discloses the following method: at the inner wall of a trench, an oxide film (oxide layer) and a silicon-rich oxide film (silicon-rich oxide) are stacked; then, the inside of the trench is filled with a silicon oxide film (silicon oxide), and the surface is polished, thereby to form a trench type element isolation part in which the top surface of the silicon oxide film embedded in the inside of the trench is flat.
[Patent Document 1]
U.S. Patent Application No. 2007/0111470
[Patent Document 2]
U.S. Pat. No. 7,645,679
[Patent Document 3]
U.S. Pat. No. 6,331,472